Using User Interaction as a pull down Selection List

When my flow executes I want to select a Host, then have VcO provide my a list of available Datastores on that host

I am able to create an array with the datastores names  (arry/String)  however when I try to pass it into a User Interaction I am not able to populate a pulldown list with the values of my array

Can someone point me in the right direction

Thanks